Guide block for engine cylinder grinding machines



J. SUNNEN Nov. 12, 1935.

GUIDE BLOCK FOR ENGINE CYLINDER GRINDING MACHINES Filed April 50, 1932 //v l/zF/VTOR. JOSEPH SUNNEN.

Patented Nov. 12, 1935 UNITED STATES PATENT OFFICE GUIDE BLOCK FOR ENGINE CYLINDER GRINDING MACHINES engine cylinder grinding machines and it consists in the novel features of construction more fully set forth in the specification and pointed out in the claims.

The present invention is an improvement over that shown-and described in my co-pending application Serial No. 233,788, filed November 17. 1927, and like the invention of said application isadapted for operation as a dry grinder, that is, without lubricating the stones with oil.

In grinders having a plurality of three or more abrasive stones rigidly arranged about a rotation axis 'it is necessary to lubricate the stones to prevent excessive chattering with its attendant screaming noise. The lubricant, interposing an oil film between the stone and the cylinder wall, cuts down the abrading efficiency of the stone and, of course, reduces the chattering and noise thereof. .I discovered and have disclosed in the application aforesaid, that if the abrading stones are arranged about the rotation axis alternately with non-abrasive elements, such as wood blocks (which serve merely as guides to hold the abrasive elements on a substantially fixed orbit as they perform their grinding operation) the stones may be operated dry without chattering. Of course, the guides must have clearance in the cylinder to permit the abrasive elements to vibrate, and this clearance must be sufficient to enable the grinder to operate most efficiently and quietly. In practical operations it has been found that a clearance of approximately .020"

on each wood guide produces the best results.

However, this clearance allows the drive shaft thrust to cause the guides to teeter on the cylinder wall. This teetering or rocking motion causes the guides to wear more rapidly toward the ends than at the middle so that ultimately the guides become rocker-shaped and must be replaced.

It is the object of the present invention to provide a grinding machine embodying abrasive elements, and guide elements cooperating therewith which operate with practically no free clearance between the face of the guide and the cylinder wall. The guides are maintained in contact with the cylinder wall under yielding pressure so they will always contact with the wall along their entire face. The yielding pressure is obtained by suitable springs interposed between the face of the guides and the holder. The tension of said springs is such that they will F hold the guides squarely in contact with the cylinder wall irrespective of the position of the drive shaft, but at the same time they will 'permit the holder to vibrate as the abrasive elements operate. Thus the guides are held against teetering as is the case with the non-yielding wood 'or'composition guides and the wear is uni- 5 form over the entire face of the guide which remains a plane surface.

It is a further object of the invention to provide guide blocks of a metallic material that will wear to approximately the same degree as 10 the abrasive elements as well as uniformly over the entire contact face of the guides. The guide material is comparatively non-compressible and also has a reasonably low coefficient of friction; it is softer than the cylinder wall and yet sufficiently friable to wear by abrading contact with the cylinder wall. In other words, it must be of comparatively lowductility. The accomplishment of these objects, as well as advantages inherent in the invention, will be better apparent from a detailed description of the invention in connection with the accompanying drawing, in which:

Figure 1 is a side elevation of my improved grinding machine with parts broken away and part of the holder in longitudinal section; Fig. 2 is a horizontal cross-section through the machine taken on the zig-zag line 2-2 of Fig. 1; Fig. 3 is an elevation of one of the guide elements looking at the working face of the guide block; Fig. 4 is a longitudinal section through the guide element taken on the line 4-4 of Fig. 3; and Figs.

5 and 6 are cross-sectional details taken on the lines 5-5 and6-6 respectively in Fig. 4.

Referring to the drawing, I represents the tool holder of a Sunnen cylinder grinder of the type described in the above referred to patent application, said holder being suspended by yoke 2 and collar 3 from a drive shaft 4. The collar -3 is pivotally connected to the holder I by means of studs 5, 5, and the yoke 2 is pivotally connected to the collar by means of studs 6, 6 so that a universal joint connection is formed between the shaft 4 and the holder I. The holder l is provided with .a longitudinally disposed axial bore I within which is housed a pinion shaft 8 rotatable by means of the adjusting head 9 for the purpose of extending and retracting abrasive elements iii, l0 and guide elements H, II comprising the tools carried by the holder. The construction and the operation of the tool holder, comprising the parts just described, is substantially the same as that of the holder of my hon- .ing device described in detail in the aforesaid patent application and will not be further described herein except insofar as necessary to explain the operation of the guide elements II, II.

The abrasive elements It, III are substantially the same as those of my application aforesaid, being supported in the holder by rack bars ID, .III which mesh with pinion shaft 8 in order that they may be extended or retracted thereby. The'guide elements II, I I are disposed between the abrasive elements IU, Ill, and each element II comprisesa mount l2 having a pair of rack bars I4, I4 extending rearwardly therefrom and a guide block I3 carried by the mount. The rack bars I4, I4 are adapted to traverse openings I5, I5 in, the holder I, which openings intersect the axial bore I so that the teeth t of pinion shaft '8 will mesh with the teeth t of rack bars I4, I4, whereby the guide elements I I, II will be extended and retracted simultaneously with the abrasive elements I0, II). In order that the abrasive elements I 0, II] may perform their grinding function they are adjusted into close operating contact with cylinder wall C and are maintained in non-yielding contact with said wall. However, it is essential that the guide elements. I I, II make yielding contact with the cylinder wall. In other words, a certain clearance must be maintained between the cylinder wall and the guide elements in order that the grinding machine will function smoothly and quietly. .As above explained, in the grinders as heretofore constructed this clearance was in the form of a clear space of approximately .020, but in the present instance this clear space has 7 been abandoned and in lieu thereof a clearance under pressure is maintained. That is to say, the guide elements are maintained in contact with the cylinder wall but are free to yield under 'the vibration imparted to the tool in operation and a limited resilience of the guides is thus obtained, although the guide blocks I3 are composed of non-resilient'material; This will be better understood from 'a detailed description of the construction of the guide elements.

Referring to Figures 3 to 6 inclusive, it will be observed that the body I6 of the mount I2 is L- shaped in cross-section, the back I'I thereof being longer than the side wall I8, said back and side wall being connected by end walls I9, I9. The rack bars I4, I4 project rearwardly from the back I I to which they are rigidly secured, and the metallic guide block I3 is positioned in the mount body I6 and securely held therein by means of pins 2|, 2| driven through openings 22, 22 in the end walls I9, I9 and into countersunk bores 23, 23 extending a considerable distance into the guide blocks I3 from the ends thereof. It will be observed (Fig. 4) that the pins 2 I, 2| are bent so that after they have been driven into the bores 23, 23 they will contact at approximately their middle point a with the enlargements 23', 23' of bores 23, 23 and operate to hold the block I3 clear of the back I! of the mount body. There is thus provided a clearance space b between therear face 24 of the block I3 and said back II. If pressure is exerted against the working face 25 of the block the pins 2|, 2| will tend to be straightened as said block moves toward the back and the clearance space 12 will be reduced. In order to prevent any tendency of the block I3 to rotate about the pins 2|, 2| as an axis, a lug 26 is provided on the rear face 24 of the block, said lug operating through a slot '21 in 'the'back I! of the mount body. The pins 2|, 2| are'of spring steel and when straightened under pressure perform the function of springs is not of uniform width but is reduced by a re 1 cess 1 formed in one side and a recess 1'' in the opposite side so that the medial portion of face 25 presents but a comparatively narrow edge 28 to the cylinder wall. This reduction in the amount of wearing surface 25 at the middle of the block compensates for the greater pressure exerted at the ends of the block on account of the vibrating action of the grinder while in operation.

It is also desirable'that the face of the block should not wear off too rapidly. The wear on the block should (preferably) approximate the wear on the grinding elements so that the amount of guide clearance initially provided for when the grinder is first put into operation may be maintained. This clearance as above pointed out is about .020" on each guide while the clearance on the grinding elements is negligible. Now, as the grinding elements wear the guide blocks will also wear at approximately the same speed so that a readjustment of the grinding elements reestablishes this initial clearance. This 1miformity of wear between guide blocks and grinding elements is obtained by forming said blocks of metal instead of wood or the various compositions heretofore employed. I

The metal of which the guide blocks I3 are composed must have certain definite properties in order to be available for this purpose. It must be possessed of a sufficient degree of hardness in order to maintain its shape in use. It must have considerable tenacity together with friability so that it will wear by attrition, that is, its surface must grind off in use and not tear .or spread, which also requires that the degree of ductility be controlled. It is also essential that the guide blocks be composed of a metal having a relatively low coeflicient' of friction. Heretofore rubber guide blocks have been used with some degree of success, and while they possess the advantages of resilience, giving a yielding contact with the cyli'nder wall, they introduce excess friction in the operation of the grinder. I have found that a zinc alloy containing in excess of 85% zinc with aluminum and copper gives the metal the desirable properties. However, I do not wish to be restricted to this particular alloy' as the invention contemplates guide blocks for cylinder grinders composed of any metal or metallic alloy having the properties herein enumerated. As far as I am aware no cylinder grinder has ever been devised heretofore wherein the tools consisted of abrasion grinding elements and metallic guide elements.

Having described my invention, I claim:

1. In a grinding machine, a mount having a' 4. In an engine cylinder grinding'machine, the combination with a series of angularly arranged elongated abrasive stones adapted for operation over the cylinder Wall to grind the same, and a plurality of angularly arranged guide elements each comprising an elongated block co-extensive with the abrasive stones and adapted to cooperate therewith, each of said blocks being formed of an alloy of zinc and being adapted to wear by attrition as they are operated over the 10 cylinder wall.

JOSEPH SUNNEN. 

